from tkinter import *
from random import randint

root = Tk()

canvas = Canvas(root, width=200, height=200)
canvas.pack()

def click(event):
    if canvas.find_withtag(CURRENT):
        canvas.itemconfig(CURRENT, fill="blue")
        canvas.update_idletasks()
        canvas.after(200)
        canvas.itemconfig(CURRENT, fill="red")

for i in range(100):
    x, y = randint(0, 200-1), randint(0, 200-1)
    canvas.create_oval(x-5, y-5, x+5, y+5, fill="red")

canvas.bind("<Button-1>", click)

root.mainloop()